1. Field of the Invention
The present invention relates to a method of controlling an operation recovery for various electronic devices, apparatus, or the like when a system reset occurs because of an anomaly in the electronic devices, the apparatus, or the like. More particularly, the invention relates to a recovery control method for a vehicle control system.
2. Description of the Related Art
In an electronic control system, when a system reset is performed due to, for example, a power supply anomaly that triggers the system reset, it is desirable to quickly recover the state immediately before the anomaly occurred. An apparatus that is configured from this viewpoint is publicly known and well known. The apparatus is provided with a backup memory for storing various data related to operations of the system, and is configured so that it can distinguish the stored data between before an update of the stored data and after the update, to facilitate selection of the stored data necessary at the time of recovery and to make a smooth recovery process possible (for example, see JP-A-7-175501).
In such an apparatus, it is typical that a system halt or a system reset is performed once such an anomaly occurs in which power supply voltage becomes less than a predetermined reference voltage, for example. However, depending on the system, there are cases in which it may be convenient not to perform the system halt immediately when a power supply anomaly occurred only one time, with such a system that the power supply anomaly occurs a plurality of times with a cycle that is unique to the system. For example, with such an apparatus as a vehicle control system, an accurate recovery process according to the frequency of occurrence, the cycle of occurrence, and the like, of power supply anomalies is desired.